Problem: Multiply, reduce to lowest terms, and write as a mixed number: $ 3\dfrac{3}{4} \times 2\dfrac{4}{5} $
$ = \dfrac{15}{4} \times \dfrac{14}{5}$ $ = \dfrac{15 \times 14}{4 \times 5}$ $ = \dfrac{210}{20}$ $ = \dfrac{21}{2}$ $ = 10 \dfrac{1}{2}$